Overview of single-cell–based discovery vs validation approaches. Single-cell approaches such as WGS or WES and single-cell RNA sequencing (scRNAseq) aim to capture information across several parameters and to yield an unbiased global assessment of the genome and transcriptome; hence, they are suitable for discovery. Because of the relatively high cost of generating these complex data, a typical study design focuses these assays on relatively few samples composed of a limited number of single cells. Conversely, targeted approaches use defined primers or antibodies to screen a limited number of parameters but with high sensitivity and statistical confidence. These assays have typically been used as a validation approach, which has the advantage of assessing many more independent patient samples. qPCR, quantitative polymerase chain reaction; scWGS, single-cell WGS.